One of the specific aims of this application is to examine the physical characteristics of DNA:protein interactions between NFAT-1 (nuclear factor of activated T cells, a trans-activating factor that binds to a cis-acting element in the interleukin-2 [IL-2] enhancer) and cognate sites. These sites include those in the IL-2 enhancer and HIV LTR (long terminal repeat). Another goal of the investigator is to try to purify NFAT-1. The applicant also proposes to analyze the ability of the putative NFAT-1 binding site in the HIV LTR to confer inducible transcriptional activity to a linked promoter. Lastly, Dr. Edwards will try to explore the function of NFAT-1 in the life cycle of HIV, including a potential role in the initial infection of susceptible T cells and the possible involvement of NFAT-1 in the breakdown of latency. Preliminary data obtained by the applicant suggest that recognition sites for NFAT-1 have remarkable sequence divergence. Consequently, she is interested in examining the correlation between in vitro binding characteristics of NFAT-1-binding sites in IL-2 and HIV and their ability to influence the level and inducibility of transcription in vivo.